I am just curious, I have a stock 87 350 cam, which I belive had.404/.415 lift at .50 and 202 207 duration and a 114.5 center. Assuming I could let the car breath all the way up and supply enough fuel, how high could this cam rev. I know there are other limitation in the engine, but I am talking just about the cam. I know there are many race cars, not drag, that use low lift short diration cams that cam handle way up to 7500+ is it possible for this cam to handle say 6000+. Thanks.

------------------
87 GTA 350 L98
K&N filter, beefed up TH-700r4, Accel Manifold, Ported Plenum and Runners, Fuel Press. Regulator 49.5psi, air foil, modified MAF, SLP cold air box, Hypertech Thermomaster chip w/160 thermostat, MSD 6AL and Blaster 3, B&M shift kit & megashifter, Moser Ford 9in Rear with Richmond 3.50 and locker, Edlebrock TES headers and Cat Back,Gutted cat, removed emissions, Hotchkis setup in rear, Poly suspension and Koni in the front, relocated MAT, bypassed TB coolant, 300 lbs lighter

 

Stock cams usually run out of power between 5000 and 5500 rpm. Lift and duration are only 2 parts to a cam profile. Race cams have a narrow LSA. They can go as low as 106 degrees. There's also a valve overlap. Think of that as how long both valves are open between when the exhaust is closing and the intake is starting to open. Stock cams have this extreamly wide to help the intake air force out the exhaust. By closing up this angle more of the intake air is kept in the cylinder to make power.

A cam like you're thinking is as simple as a stock eliminator camshaft. They are limited to .430 lift or OEM whichever is higher. Duration, LSA and overlap are totally open to any spec. Many of these engines rev to 7500 rpm.

------------------
Follow my racing progress on Stephen's racing page
and check out the race car

87 IROC-Z SuperPro ET Bracket Race Car
461 naturally aspirated Big Block

Best ET on a time slip: 11.242 altitude corrected to 10.69
Best MPH on a time slip: 121.52 altitude corrected to 127.76
Altitude corrected rear wheel HP based on power to weight ratio: 504.5
Best 60 foot: 1.546

Racing at 3500 feet elevation but most race days it's over 5000 feet density altitude!
Member of the Calgary Drag Racing Association

87 IROC bracket car, 91 454SS daily driver, 95 Homebuilt Harley

 

Does this mean that even if I can provide breathing power and fuel with say bigger injectors and a superram that I still won't have any power beyond 5500 rpm. I realize that to take full advantage of them I would need to replace the cam, but I am just wondering if I will be able to rev higher with these mods. Thanks.

 

Stock cams are set up for smooth idle and low emissions. Neither of these things is consistent with high-RPM operation. Like Stephen said, there are alot of other aspects of cam design besides just gross lift and duration, that go into determining the RPM range where the cam makes meaningful power.

The stock cam was carefully optimized for the induction system it's paired with. It will not work well with any other tuning of the intake tract. If you're going to spend all the money and do all the work of changing out all of that, it makes no sense whatsoever to leave the weakest link of the whole thing in place. Think of it this way: what difference does it make how big you make the intake tract, that is how much it will flow, if all you do is barely crack the valve at the end of it for just a brief instant? So in that sense you are right, no matter what size runners and injectors you bolt on, with that puny little cam in there, the motor will not make power at any significantly higher RPM than it does now.

Again, like Stephen said, there are racing classes (in the larger world of racing, not so much in just hobby drag racing) where they limit cam lift and/or duration to either the stock specs or to some pre-determined amount; the cam companies make what they call "stocker" cams where the lift and duration measurements are the same as stock, but the lobes are like square instead of pointy, to hold the valve as far open as possible for as long as possible.

------------------
"So many Mustangs, so little time..."
ICON Motorsports

[This message has been edited by RB83L69 (edited May 24, 2001).]

 

Well thanks guys, it looks like my next project should be a cam and maybe a new timing set. But let me ask just one more question. Say I step up to a new Lingenfelter or SLP cam that is computer friendly will I need to have a new prom burned. I currently have a Hypertech chip, but I know that is just a little better than stock. So will a new more aggressive cam and maybe heads too, require a new chip, thanks.

------------------
87 GTA 350 L98
K&N filter, beefed up TH-700r4, Accel Manifold, Ported Plenum and Runners, Fuel Press. Regulator 49.5psi, air foil, modified MAF, SLP cold air box, Hypertech Thermomaster chip w/160 thermostat, MSD 6AL and Blaster 3, B&M shift kit & megashifter, Moser Ford 9in Rear with Richmond 3.50 and locker, Edlebrock TES headers and Cat Back,Gutted cat, removed emissions, Hotchkis setup in rear, Poly suspension and Koni in the front, relocated MAT, bypassed TB coolant, 300 lbs lighter

 

Yea, change the cam. I ran a quick test on my Desktop Dyno2000 with the specs that you posted. Using TPI, stock heads, 9.5 comp., and headers w/mufflers, that cam loses HP after 4500 RPMs. That's using the 114.5 as the LSA. I set Intake Centerline about the same, cause that's about what GM uses. If you post the specs for the SLP or Lingenfelter cam, I can give you and idea of what it'll do.

------------------
92 RS w/t-tops 305 TBI Auto.
170K miles and don't burn a drop o'oil
-K&N Truck filter #1500 w, open ele.
air cleaner
-Dynomax 2 1/2" cat-back
-B&M TransPak
-Jet Stage2 Chip
-180* T-Stat w/ 185* Fan Switch
-JVC CD--Alpine speakers & 4ch. amp
Rockford 2ch. to 2 MTX 12" subs

[This message has been edited by AJ_92RS (edited May 24, 2001).]

 

Something else I didn't mention but was touched briefly on "stocker" cams. Advertised duration and duration at .050 mean a big thing. You can have 2 identical cams. Lift, advertised duration, LSA, overlap. One has 230 duration at .050 but the other has 250 duration at .050. The second cam is opening the valve sooner and holding it open longer. IE. almost square. Although it has the same lift, duration, etc as the other cam it will perform much differently.

That's why CompCams Xtreme energy cams have become so popular. They have close to the same specs as a regular cam but the ramps are more aggressive.

Cam manufactures spend a lot of money designing their cams. The best way to get the best cam for your combination is to call them. Once they have all the information about your car, they will recommend the best cam for your application. It's better than guessing on a cam then finding out it's not what you needed.

[This message has been edited by Stephen 87 IROC (edited May 24, 2001).]